Radio control system



Aug. 30, 1949.

E. 5. PURINGTON RADIO CONTROL SYSTEM Filed July 7. 1944 I AMPLIFIER Il .us I :I/ "9 AMPLITUDE MODULATOR A (a) yea 'LIQ H l3 l2 PULSE FORMING cmcun' INVENTOR ELLISON Patented Aug. 30, 1949 Ellison (Home by mesne'a ssign nnfts, to a eta dlo Corporations-6i I mer ies, New Yorli, N. Y., a. corporation of Delaware A pneatiomiumviis ii seriambz 5433B 'ffihisinvention relatesito:airadio-controlsystrn- I of.- thetype utilizing; aapair of transmission channels which; are selectively. pulsed in: timed se quence, and has for anpbjlect to provide. a system offtheabove type utilizing a single transmitter which is-modulated to propagate pulses alternatel-"yand intimedrsequence qn the respective channels. Other objects and advantages willibeapparent" asthe naturef the invention more: fully" diselosed= .l

a copending; application-Sen 36,10 4, fi ledf May; 18,-, 195*4? now U: S. Patent; No. 2,465,925; gnanted March 29;, 1949; a complete system for radio control or signalling has beendisclosed involving: two independent: radio transmitterswith the sensezof control-=01 'si g-naldetermined. by the pulse sequence. A receiver selective to the various pulsesequencesfor actuating selected oontrolor signal-circuits: The present; invention I relates-to: a transmitter having; novel: and irr 0111b more particularly in the claims appended hereto, the invention itself will be better understood by referring to.- tha following? description; takenrin connectionwithithe accompanying draw ings; in: which aspecific embodiment thereof has: heen set forth for the-purposesof illustration: H

Inthe drawings: The; figure; a schematic. dia'gramt of: a. transmitter embodying the. present inventions v Referring: to" the drawings, block- W represents 85- pulse; forming: circuithaving pulse output terminal'ssl t and) I 2: and a-commomreturnconnected toxae terminal IS; The pulse forming circuitds adapted to form a -pulsfe w at the terminal ll f-ollowecibyv eta-similar pulse b: at the: terminal l2, the? pulses -avahdr b being: positive voltage pulses with? respect to the.- common return: on groundtefminal r except when a;- pu-lse' ocburs, the) terminals: Hi and 1-2 are atgroundpotential;v The pulse moe" nientarily raises the terminal l1 above ground etentiairand then momentarily raises. the; t'e'r:-'

minal [2 above ground potential. Onet pe of; areas suited for producing such pulses" at the terminals H;- 12 sea IZFiS sliovvn more in detail:

triece-yse'fiaine appuaa mn ahov'e mentioned 0 The arrangement is suchthat; V

11' Cltiinis. (01250 -17 I 'rii. reversing. switeri zli' provided: with st tg ha'ry' contacts 21' and" 22; vvh'i'c'h' arei amiected" through zgnqns rs .2 3 a dj 24"respctive'ly tothe, i-npugggnus. 25 anu 265 or was pulsing'i trusses: 2T angrlza oim. sin-sub ersion an. 7 4

This cirou'it 3a includes-T the; pulsing triodes 21% triod esi 3 3i afitlls f4 Th cathodes: 35' and 36. ans the platesS-l-arld B- of the triodes'fi' and 31 which ,1 maybe contained-i tlie sariie envelope'; are mswn En land 40 are connected by" a line 1 3 to ai grounded line A source of negfative grid was, shown-*- as a lcfattery isconnected through resistors d5" and- 41 to m gmas 25" and; 26 of the triodes 2-7; and 28 respectivelj. ,Battervi E, am a battery SBEconnected inseriestherewith, furnish negative g rid bias to-the grids liliand 52: of the triodes 3 land: 32 through the resistors B and 5f}- respectively y A- source' of plate potential; showrr as; a battery 55, is; connected throug'lli' resisters 55: andB-t to supply plate voltage to the anodes-31 and Q8 and to; the anodes ll r ne The a i o nt al, swell by the source 45 so-chosen thatin the-absence: of a: pulse frOm the plllse forrningz circuit; l fl; no current passes through either the triode 21 or the triode-za p r T'he: anodes tl and; 4 2: are connected. through a resistor so to the grid- 5 of t de n the' anodes 31' and 31% are connected: through a resistor El tcithey grid 52- ofthe triode- 32;; The

triodes; strand 34 areprovideirl with grids 6-2 and 63 which? are: connected to the grids 51 and: 5-2 respectrvel-y and anodes 6j4 and-fi5 which areconne'cted toethspositivevoltagesource 551? Gathodes 66 and 651 of trioc'les 36- and: 34* areconnected through: resistors? 68. and? 69- respedtively' to the source of biasin voltage 45.

this circuit the tubsf 3-1 arid 732* are cross connected "lo'v dire'ct' coupling; from the plate of eachi to the grid of the other; Such a systemposse'sses" two positions of stable equilibrium: in which one of l the: whesdraws a" large: amount;- of plate cur-rent viithn smajllliiasi'on its gridiandsth oher draws a; small amount ofi plate cui'rentvwith a lerg e bias onzitsigrids 'Thefcircuit constants'mav be so choseni'thati eaohs of the tubes 31: and? 3:2 mews current only when its? grid: is? at? substanunmeanhsaiamazennan For eiiimpl'? prior'f t'o tlle :arriv'ak of: thepulses tHe tiibe STmav be assumect to be fiassmg durrent;

3 thereby producing a voltage drop through the resistor 51 which reduces the voltage on the anodes 4| and 42. Due to the direct coupling through the resistor 60 to the grid 5| of the tube 3| a highly negative bias is supplied to the grid 5| which biases the tube 3| beyond cut-oi! so that no current flows therethrough or through its plate resistor 56. Since no current flows through the resistor 56 the anodes 31 and 38 are substantially of the potential of the positive terminal of the source 55 and due to the direct coupling through the resistor 6| to the grid 52 the latter is at a higher potential than the grid 5|, for example, at cathode potential.

This condition of voltage and current will continue until influenced by the operation of the pulsing of tube 21. When a momentary pulse is applied to the grid 25 of this tube as by a pulse received through line I5 from a terminal I I, the tube 21 becomes conductive and plate current is caused to flow through the resistor 56, causing a voltage drop in this resistor which, due to the direct coupling through the resistor 8| to the grid 52 of the tube 32, increases the negative bias of the grid 52 beyond cutofi so that current flow through the resistor 51 is interrupted. This, in turn, causes an increase in potential of the anodes 4| and 42, which is applied through the resistor 60 to the grid 5| of the tube 3| to increase the potential of the grid 5| and cause the tube 3| to pass current. After the pulse on the input of the tube 21 has passed, the tube 21 will again become non-conductive, but the tube 3| will continue to pass current. Hence, the current through the resistor 56 will decrease somewhat but insufficiently to cause the tube 32 to pass current. Therefore, the tube 3| continues to pass plate current with its grid biased near cathode potential.

Hence, as a result of a momentary pulse on the tube 21, the tube 32 which was previously conducting becomes non-conducting, and the tube 3| which was previously non-conducting becomes conducting. This state of stability will hold until a pulse is applied to the grid 26 of the tube 28 from the terminal I2 which momentarily causes the tube 28 to become conducting and through a process similar to that above described changes the biasing voltages on the tubes 3| and 32 so that the tube 3| becomes non-conducting and tube 32 becomes conducting.

As a result of the above operation, the grid 5| of the tube 3| remains highly negative except during the interval between the pulses a and b at the terminals I I and I2, but during this interval the voltage of the grid 5| rises. Similarly, the voltage of the grid 52 of the tube 32 is highly negative during the period between the pulses a and b, but rises outside of this period. Therefore, the circuit establishes two oppositely phased pulses at the grids 5| and 52 with the length of the pulses equal to the time interval between the-two control pulses.

The triodes 33 and 34 are cathode following tubes or repeater tubes provided with plates 84 and 65 connected to the positive end of the source 55 and with cathodes 63 and B1 normally negatively biased through the resistors 68 and 69. The tubes serve as repeaters of the impressed grid votage without phase reversal and are desirable to prevent the subsequent work circuits from disturbing the action of the flip-flop circuit 30.

Two grid-modulated high frequency oscillators 15 and 16 are designed to produce output voltages of frequencies f1 and f2 respectively. The oscillators 15 and 1 6 are provided with grids 11 and 18 connected through resistors 19 and 80 to a ground l'ead 8|. Taps 82 and B3 on resistors 19 and 80 are connected by lines 84 and 85 to the cathodes 66 and 61 of the tubes 33 and 34 respectively. The resistors 19 and 80 may be by-passed to ground by condensers 86 to 89.

The plates of the triode oscillator tubes15 and 16 are connected through oscillatory circuits 90 and 9| respectively to the positive end of a plate battery 92, the negative end of which is grounded to the lead 8|. Tapped inductors 93 and 94 are connected from the cathodes of the triodes 15 and 16 to ground and low impedance condensers 95 and 96 are connected from the cathodes to taps 91 and 98 on inductors 99 and I00 for transferring of alternating voltages from oscillator circuits 90 and 9| respectively to the cathodes.

After the arrival of the pulse b and before the arrival of the next pulse, the oscillator 16 is in oscillation but the tube 15 is not oscillating since its grid circuit is biased negative to cut ofl" by the cathode 66 of the tube 33. Upon the arrival of the pulse a with the consequent reversal in grid potentials in the tubes 33 and 34, the grid of the tube 16 is caused to become highly negative,

thereby stopping that tube from oscillating whereas the grid of the tube 15 is raised in potential to permit that tube to begin oscillating. This condition holds until the next pulse 12 is received at the terminal I2 which reverses the action and causes the tube 15 to stop oscillating and the tube 16 to begin oscillating. Therefore a voltage of frequency I2 is produced across the inductor 94 during the interval between pulse b and the next pulse a and a voltage of frequency ii is produced across the inductor 93 during the period between the pulse a and the pulse b.

These voltages f1 and is are applied by lines |0| and I02 respectively to the control grids I03 and I04 of pentodes I05 and I06 which are connected to constitute a combining circuit. The cathodes of the pentodes I05 and I06 are connected together and are positively biased by battery I08. The screens of the pentodes I05 and I06 are connected together and are positively biased by battery I01, and the plates are fed from the positive end of a battery I09 through a choke I I0.

The plates III are connected through a low impedance condenser I I2 to a coupled circuit network comprising inductances H3 and H4 and condensers 2|5 and 2|6 which are designed to have maximum frequencies of response at the frequencies f1 and f2. These frequencies may. if desired, be separated widely on a percentage basis with, for example, frequency f2 50% higher than frequency ii. The details of construction of such a coupled circuit network per se are well known and need not be described herein.

In the embodiment shown, the network is connected by a line II 5 to an amplifier IIB of any standard design which is capable of amplifying the two frequencies f1 and f2. The amplifier H8 is coupled by lines M1 to an amplitude modulating circuit II8 of standard construction, which in turn is connected to radiators H9 and I20 which are suited to radiate waves of frequencies f1 and is.

The terminals I1 and I8 of the double throw switch 20 are also connected by lines I25 and I26 to the input circuits of space discharge tubes I21 and I28 respectively having grids I29 and I38 which are grounded through resistors I3| and I32. A battery I33 is shown as connected to supplygrid biasing potentials, The devices I21 and I28 are also provided with plates I35 and I36 connected s:- through at resistes PW a 131366 tiiirl Ifl through a condenser- I39? to am arti ficial line l423 compri'sii'ig series inductors I44 and shunt condensers M2 and terin' i netted inan out" put resistor lust The voltage drcp across the re- The pulses terminals I I: aiid 12 are conibihe'd iii the plate circui'ts ofi the: tubes li l and pass to the amti ficial transmission line Mr succession: to roduce negative voltage ulses across thermistor manner-1i are usecrto amplitude modulate the: signer from the ampli l l fi. 'l he pulsesare delayejdby'the artifioihl transmission lihe'i I an amount such that? the pulses do not arrive at the mod-mater: during periods of change over from nequency'jstd fre queney fsandvice'versas the-pulsed will modulate: the transmitter t is opera-ting: frequency n andtne pulse l5 1' modulatev the transmitter when: it operating at the ma line: transmitter is prererablyorthe type-wmen takes plate: current only when negatively" pulsed,- du i l ngi which tim'e' it propagates from'theantenna" system M 9;- t-Zil whichever of thetwo frequencies is: thenimpressed upon the amplifier 6 from use: lil 5. Withthe reversing switch 20in one pothe: transmitter will= radiate on the ire-- quencw when modulated; the pulse-a and' on' frequency-f2 wheh mod-iflate'd by'the pulse b. With the? reversing switch 20: in the opposite position the transmitter Wilt radiate on: the frequency is when modulated by the pulse a and on the ire-- queiieyfizwlieh modulated ldy the pulse b. The reversing switch accordingly determines the sequence of the pulses on the" twofrequencies.

As pointed out in the (so-pending application above identified, the selected pulse'sequence may be utilized for selectively energizing. control circuits at a receiver so that one type of control is producediwith the reversing switch in one post tiomand another typelof-controlistproduced with the; reversing switch in the opposite position;

'l hetransmitter is thus frequency'modulated. to

selectively operate on. frequencies 11 and f2 and is also amplitudemodulated bypul'ses a and b in accordance' with the timing of: said pulses.

Although a specific embodiment. of the" invention has been shown for purpose of illustration, it is to be understood that various changes and adaptations may be made as will be readily apparent to a person skilled in the art. The invention is only to be restricted in accordance with the scope of the following claims.

What is claimed is:

1. A radio signalling system comprising radio transmitting means including a source of signalling energy and a radiator connected to propagate said energy, a source of a series of energy pulses having a, predetermined time sequence, means modulating the frequency of said transmitting means in response to successive pulses to cause said transmitting means to operate alternately to propagate energy over a pair of different frequency channels, means modulating the amplitude of the transmitted energy by said pulses including timed means to cause alternate pulses to be radiated on diflerent frequency channels, and means controlling the sequence of said pulses with respect to said channels.

2. A radio signalling system comprising radio transmitting means and a radiator connected thereto to propagate radiant energy waves, a source of a series of energy pulses having a predetermines timesequence; means responsive to: said pulses to modulate said transmitting. meansihifreqnency and in amplitude in a manhe r to propagate alternate: pulses on different frequency channels, and.- means controlling the. sewensaotsaid pulsesw-ithrespect to said charrnlsa a r A radio signalling system. comprising radiotransmitting means including sources of oscillations ofi difl erent frequencies, a sourceof a series of "ener'gy pulses having. a predetermined time. sequencetmeans responsive to successive energy pulses to render' saidoscillation sources alternairtiveliy operative, additional means responsive to said energy pulses for modulating the amplitude oi saii'zl oscillations in a manner such that alternate-pulses are radiated over different frequency chapai els',- and; means. controlling the sequence. of

saitlpul'seswi th respect to said channels.

A's. radio signalling system comprising a pair of oscillators connected to operate respectively at different frequencies, a source of a series ofenergy. pulses having a predetermined time se-' quenceimeans responsive to successive pulses for alternately energizing the respective oscillators, a transmission channel, means supplying oscilla tions from said oscillators thereto during successive periods means responsive. to said pulses, includingpulse' delaying means, arranged to aniplimdamodulatesaid channel during said. successive periods; and meanscontrolling the sequence o'fsaid pulses with respect to said ire quency.-periods.

5: Ara'dio'signalling. system comprising a source of? arseries of energy pulses: having at predeter-. mined. time sequence; a pair of space discharge devices connected to be: energized alternately by 'successivepulses,means causing each of said devices; when energize-d tocontinue to pass current until deenergized" by the-succeeding energy pulse, a; pair: oi)- oscillators operating at different frequencies,. means responsive to passage of current by said last. devices to cause said oscillators to operate alteriiately'during' the respectiveperiods,

i si -transmission channelreceiving said oscillations,

andemeans'connected to amplitude modulate said channel in accordance with said pulses so that'- siiccessive pulses modulate said channel when? the latter is: operating." at difierent frequencies.

6. A radio signalling system comprising a source of a series of energy pulses having a predetermined time sequence, a pair of space discharge devices connected to be energized alternately by successivepulses, means causing each of said devices when energized to continue to pass current until deenergized by the succeeding energy pulse, a pair of oscillators operating at different frequencies, means responsive to passage of current by said last devices to cause said oscillators to operate alternately during the respective periods, a transmission channel receiving said oscillations, and means connected to amplitude modulate said channel in accordance with said pulses, said last means including a delay circuit connected to delay said amplitude modulation pulses to coincide with the different frequency periods of said channel so that successive pulses modulate said channel when the latter is operating at difierent frequencies.

'7. A radio signalling system comprising a source of a series of energy pulses having a predetermined time sequence, a pair of space discharge devices connected to be energized alternately by successive pulses, means causing each of said devices when energized to continue to pass current until deenergized by the succeeding energy pulse, a pair of oscillators operating at different frequencies, means responsive to passage of current by said last devices to cause said oscillators to operate alternately during the respective periods, a transmission channel receiving said oscillations, means connected to amplitude modulate said channel in accordance with said pulses, said last means including a delay circuit connected to delay said amplitude modulation pulses to coincide with the different frequency periods of said channel so that successive pulses modulate said channel when the latter is operating at different frequencies, and means controlling the sequence of said pulses with respect to said frequency periods.

8. A radio signalling system comprising a source of a series of energy pulses having a predetermined time sequence, a pair of space discharge devices connected to be energized alternately by successive pulses, means causing each of said devices when energized to continue to pass current until deenergized by the succeeding energy pulse, a pair of oscillators operating at diiferent frequencies, means responsive to passage of current by said last devices to cause said oscillators to operate alternately during the respective periods, a transmission channel receiving said oscillations, means connected to amplitude modulate said channel in accordance with said pulses, said last means including a delay circuit connected to delay said amplitude modulation pulses to coincide with the different frequency periods of said channel so that successive pulses modulate said channel when the latter is operating at different frequencies and a reversing switch connected to control the sequence of said pulses with repect to said frequency periods.

9. In radio signalling apparatus, a source of recurring energy pulses separated by like time intervals, a transmitter, oscillatory energy generating apparatus coupled to said transmitter and controlled by said pulses to supply to said transmitter pulses of energy the frequency of which alternates from a first frequency to a second frequency, sending means connected with said transmitter, an amplitude modulator in said transmitter, connections for impressing said pulses from said first mentioned source on said amplitude modulator, and a time delay network in said last named connections.

10. In radio signalling apparatus, a source of recurring energy pulses separated by like time intervals and having a predetermined time sequence, a transmitter, oscillatory energy gen- 7 erating apparatus coupled to said transmitter and controlled by said pulses to supply to said transmitter pulses of energy the frequency of which alternates from a first frequency to a second frequency, signal sending means connected with said transmitter, an amplitude modulator in said transmitter, couplings for impressing said pulses from said first mentioned source on said amplitude modulator, a time delay network in said last named connections and a pulse sequence reversring switch in the coupling between said first source and said apparatus and said first source and said modulator.

, 11. In radio signalling apparatus, a source of energy pulses separated by like time intervals and having a predetermined time sequence, a transmitter, oscillatory energy generating apparatus coupled to said transmitter, a switching circuit including two tubes coupled to said apparatus and coupled to said first source to be alternately conductive in response to said pulses to key said REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,181,568 Kotowski et al Nov. 28, 1939 2,282,102 Tunick May, 5, 1942 2,376,395 Skellet May 22, 1945 FOREIGN PATENTS Number Country Date 540,233 Great Britain Oct. 9, 1941 

